Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Area IV of the Santa 

Susana Field Laboratory

SEC-00235

Lara Hughes, PhD, CHP

Health Physicist

Division of Compensation Analysis and Support

Advisory Board on Radiation and Worker Health, 118th

Meeting

Santa Fe, NM

August 23-24, 2017
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Previous SEC classes for Area IV SSFL

Petition 

Number NIOSH recommended SEC class

SEC-00093 All covered employees, all areas of Area IV SSFL, Jan. 1, 1955 - Dec. 31, 1958

- based on lack of internal monitoring pre-1959

SEC-00156 All covered employees, all areas of Area IV SSFL, Jan. 1, 1959 – Dec. 31, 1964

- based incomplete bioassay data available to NIOSH pre-1965

SEC-00234 All covered employees, all areas of Area IV, SSFL, Jan. 1, 1965 – Dec. 31, 1988

- based on insufficient data to assess intakes from thorium and americium

SEC-00235 None
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Petition Evaluation History

 Petition SEC-00235 received August 9, 2016 for class: 

All employees of North American Aviation, to include corporate 

successors and subcontractors who worked at Area IV of the SSFL 

from December 31, 1964 through present.

 Class evaluated was:

All employees of the DOE, its predecessor agencies, and their 

contractors and subcontractors who worked at Area IV SSFL in 

Ventura County, CA, from Aug. 1, 1991 through Jun. 30, 1993 

 NIOSH proposed class to be added to SEC: None
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Controls for Environmental Pollution 

(CEP)

• Petition did not adequately support any of the defined bases

• CEP was suspected of data falsification and results are not used by 

NIOSH 

• NIOSH considered petition basis F.2 supported (lost, falsified or 

destroyed records)

• Area IV used Controls for Environmental Pollution (CEP) as the urine 

sample analysis vendor from August 1991 to June 1993

• Research found documentation of contract end in June 1993 

• Evaluation to determine if there is any impact to DR due to the 

discarding of CEP data
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Area IV SSFL claims as of July 2017

Total Number of claims submitted for DR 316

Total number of claims for workers who worked during the period from 

August 1, 1991 through June 30, 1993

29

Total number of claims for workers who started employment during the 

evaluated period

6

Number of DRs completed for the evaluated period (submitted to DOL) 22

Number of claims with internal dosimetry records for the evaluated 

period

5

Number of claims with external dosimetry records for the evaluated 

period

10
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Area IV SSFL Site

• 2,850 acres total

• Simi Hills, Ventura County; 30 

miles northwest of Los Angeles, 

• 4 administrative and operational 

areas (Area I-IV)

• Area IV (290 acres) is the only 

covered area (ETEC)

• Contractor during 1991-1993 

period: Rockwell International
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

SSFL Processes 

• DOE operations (1955-1988)

• Reactor testing and development 

• Nuclear Support operations

• Energy and non-nuclear R&D

• DOE remediation (1988 – present)

• D&D of structures and components

• Characterization, treatment, packaging and temporary storage of 

radioactive and mixed waste
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

SSFL Processes - cont’d

• Highest exposure potential during D&D:

• SNAP Reactor Development Facility D&D

• Hot Lab: Hot cell D&D

• Facilities still operating:

• Fuel Storage Facility 

• Rad. Materials Handling Facility Complex

• Rad. Instrument Calibration Laboratory
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Site History - Timeline
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Internal Exposure during D&D

Sources: 

• Dust from demolition operations

• Removal of reactor activated concrete

• Decontamination of hot cell facility

• Unencapsulated material handled, stored and packaged in the RDMF

Radionuclides of concern: 

• Transuranics

• Activation products

• Uranium compounds

• Limited thorium and plutonium 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Internal Monitoring Data

• Internal monitoring for workers:

• High contamination areas

• Handling unencapsulated materials

• Special samples triggered by air sample results

• In-vitro and in-vivo were routine, but dependent on job assignment

• CEP was primary bioassay vendor: Aug. 1, 1991 – June 30, 1993

• CEP suspected of data falsification 

• CEP bioassay analyses for uranium, gross alpha, plutonium and 

mixed fission products are not being used by NIOSH
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Internal Monitoring Data – cont’d

• SSFL CEP bioassay were baseline/routine in nature

• Air sample data is available for the same period

• In-vivo data is available for the same period (Helgeson)

• Coworker model (OTIB-0080) is available ending just prior to 

CEP period:

• U: 1980-1988

• Pu: 1969-1986

• MFP: 1965-1991
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Uranium Bioassay Results
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Plutonium Bioassay Results
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

MFP/Sr-90 Bioassay Results
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Gross Alpha Bioassay Results
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Frequency of WBC scans
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Internal Feasibility 

• Lack of CEP in-vitro data does not cause infeasibility to bound 

internal dose for monitored and unmonitored workers

• Comparison of remediation period bioassay data to the 

operational period data showed no indication that the coworker 

intake rates would not bound the exposures for unmonitored 

workers.

• D&D and waste handling operations throughout the remediation 

period (1989-present) remained consistent in procedure, 

equipment, and exposure risk. 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Internal Feasibility - cont’d

• During the CEP period the site was performing routine in vivo

whole-body scans with Helgeson, there were no measurable 

exposures.

• In response to the DOE concerns with CEP data, the SSFL site 

initiated confirmatory resamples analyzed by the new 

contractor, Teledyne-Brown Engineering, these follow-up in vitro

results confirmed no measurable internal exposures.
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Summary

Feasibility Findings for Area IV SSFL SEC-00235 (Aug. 1, 1991 – June 30, 1993)

Source of Exposure Dose Reconstruction

Feasible

Internal

- all radionuclides X

External 

-Beta-Gamma X

- Neutron X

- Occupational Medical X-ray X